基于改进的风险矩阵法的生命线网络地震脆弱性分析

生命线网络的脆弱性不单单只表示地震发生后对网络作用而产生的后果,还应该包括网络的连通情况。本文在重新确定生命线网络脆弱性定义的基础上,运用风险评估理论中的风险矩阵方法综合考虑生命线网络的连通性能和失效后果两个方面来评价生命线网络的脆弱性,并以一个供气管网为例说明改进的风险矩阵法评价生命线网络脆弱性的有效性和合理性,找出供气管网中脆弱性等级最高的节点,分析其脆弱性等级最高的原因,以便于重点保护,并降低网络的脆弱性。     

Seismic analysis of deep tunnels in near fault conditions: a case study in Southern Italy

The importance of underground structures in transportation and utility networks makes their vulnerability to earthquakes a sensitive issue. Underground facilities are usually less vulnerable to earthquakes compared to above-ground structures, but the associated risk may be relevant, since even a low level of damage may affect the serviceability of a wide network. Seismic analysis of tunnels close to seismogenic faults is a complex problem, which is often neglected at the design stage for the lack of specific codes or guidelines for the design of underground structures in seismic conditions and also because, as mentioned above, underground structures are considered less vulnerable to earthquake loading. This paper investigates the seismic response of deep tunnels focusing on the required steps for a proper design under both static and dynamic loading. The study aims at contributing to improve the methods currently used for the seismic analysis of underground structures. At this purpose, the seismic response of a deep tunnel in Southern Italy has been investigated along the transversal direction. The infrastructure is part of the railway switch line connecting Caserta to Foggia in the Southern Apennines which is one of the most active seismic regions in Italy. The seismic response in the transversal direction has been analysed by using the pseudo-static approach as well as through advanced numerical modeling using the spectral element method coupled with a kinematic approach for finite fault simulations. The pseudo-static approach has been implemented using a closed-form analytical solution. The results obtained from advanced numerical modeling and the pseudo-static method have been compared to assess their validity and limitations.     

损失分布和非结构损失对房屋建筑地易损性的影响

房屋建筑的地震易损性是地震损失评估和地震巨灾风险模型的基础。作为房屋建筑的重要组成部分,各类非结构构件的损失在现有的易损性模型中并未得到足够重视。本文以一栋典型钢筋混凝土框架结构教学楼为对象,通过将房屋建筑中的各类构件划分为具有不同地震损伤特性和损失后果的易损性组,考察建筑内的损失分布和非结构损失对房屋建筑地震易损性的影响。分析结果表明:由于许多非结构构件在中小地震作用下即可能发生较严重的破坏,房屋建筑在中小地震下的易损性主要受非结构损失控制;随着地震动强度等级的不断提高,结构损伤渐趋严重,结构损失对整体建筑易损性的影响不断增大;在结构进入震后不可修状态之前,建筑不同楼层的损失分布是评估建筑地震损失时不可忽略的因素。     

Active Tectonics and Seismic Zonation of the Urban Area of Florence, Italy

—?The city of Florence possesses a concentration of cultural and artistic treasures which is unique in the world. In this sense it has a particularly high seismic exposure and a potentially high vulnerability. In order to better evaluate its seismic hazard and risk, we analyzed the seismic response of the urban area of Florence by performing a multidisciplinary study on the effects of earthquakes on the city. By a computer aided methodology we re-evaluated the seismic intensity reports of the May 18 and June 6, 1895 earthquakes in different parts of the city and compared these data with recent studies on surface geology, active tectonics and actual fault movements in the Florence basin. We concluded that more detailed studies of soil response are needed to form a basis for public policy.     

考虑冲刷作用效应桥梁桩基地震易损性分析

冲刷造成桩周土体的剥蚀将会削弱土体对桩基的侧向支撑能力,冲刷效应会对桥梁桩基的地震易损性产生影响,因此有必要对冲刷和地震共同作用下桥梁桩基的易损性进行研究。利用SAP2000软件建立三维桥梁有限元模型,通过非线性时程分析得到桥梁桩基地震响应峰值。采用概率性地震需求分析方法,建立不同冲刷深度下桥梁桩基地震易损性模型,在地震易损性函数假设为对数正态分布函数的基础上,通过回归分析得到概率模型中的参数,进而得到不同冲刷深度下桥梁桩基在不同破坏状态所对应的地震易损性曲线,并分析冲刷深度对桩基破坏概率的影响。研究结果表明:随着冲刷深度的增加,桥梁桩基在地震作用下的破坏概率显著增加。     

P- and S-Wave Site Response of the Seismic Network RESNOM Determined from Earthquakes of Northern Baja California, Mexico

—We determined the response to P- and S-wave incidence of the permanent stations of the seismic network of Baja California (RESNOM) using two independent methods. We selected 65 events with magnitudes between 2.2 and 4.8 and hypocentral distances ranging between 5 and 330 km. The site response of the ten stations analyzed was first estimated using average spectral ratios between the horizontal and the vertical components of motion (H/V ratios). As a second approach we performed a simultaneous inversion for source and site. In order to invert the spectral records to determine the site response, we made an independent estimate of the attenuation for two different source-station path regions. Then we corrected the spectral records for the attenuation effect before we made the inversion. Although the average H/V ratio of many sites is inside the error bars of the site response estimated with the spectral inversion, the spectral inversion tends to give higher values. For the S wave some sites show similar frequency of predominant peak when comparing the responses obtained with both methods. In contrast, for the P waves the H/V ratios disagree with the results of the inversion. In general, the site response of the stations is strongly frequency dependent for both P and S waves. We also found that the natural frequency of resonance of the sites is near 0.5 Hz for P and near 0.8 Hz for the S waves.     

Pre- and post-earthquake regional loss assessment using deep learning

As urban systems become more highly sophisticated and interdependent, their vulnerability to earthquake events exhibits a significant level of uncertainties. Thus, community-level seismic risk assessments are indispensable to facilitate decision making for effective hazard mitigation and disaster responses. To this end, new frameworks for pre- and post-earthquake regional loss assessments are proposed using deep learning methods. First, to improve the accuracy of the response prediction of individual structures during the pre-earthquake loss assessment, a widely used nonlinear static procedure is replaced by the recently developed probabilistic deep neural network model. The variabilities of the nonlinear responses of a structural system given the seismic intensity can be quantified during the loss assessment process. Second, to facilitate near-real-time post-earthquake loss assessments, an adaptive algorithm, which identifies the optimal number and locations of sensors in a given urban area, is proposed. Using a deep neural network that estimates area-wide structural damage given the spatial distribution of the seismic intensity levels as a surrogate model, the algorithm adaptively places additional sensors at property lots at which errors from surrogate estimations of the structural damage are the greatest. Note that the surrogate model is constructed before earthquake events using simulated datasets. To test and demonstrate the proposed frameworks, the paper introduces thorough numerical investigations of two hypothetical urban communities. The proposed frameworks using the deep learning methods are expected to make critical advances in pre- and post-earthquake regional loss assessments.     

基于增量动力地震易损性分析的高层结构抗震加固研究

由于承重结构构件分布不均匀,导致高层建筑框架承重构件间的距离不相等。在地震时,这种不规则分布可能引起加速度共振效应,从而导致建筑失稳。为此,以地震动强度、地震动速度峰值、最大层间位移角为参数指标,分析高层建筑的极限状态,提出基于增量动力地震易损性分析的高层结构抗震加固研究。以某实际工程为试验对象,运用ABAQUS软件构造高层建筑框架结构三维模型,选取多条地震波以及符合场地条件的地震动记录进行验证,绘制地震易损性曲线。结果表明:在高层建筑框架结构中安装阻尼器,可增强结构中各构件的承载力,改善高层建筑抗震性能;增加钢板厚度可提高结构抗震水平,降低极限状态下框架结构IO、LS与CP的超越概率;提高混凝土强度,可改善框架结构抗倒塌性能。高层结构完成抗震加固后,抗震能力由0.91提升至1.01。由此证明,以增量动力分析得到的结构易损性为基础,对建筑易损性较大的地方进行加固、完善,能够改善高层建筑框架结构地震易损性,减少地震灾害损失。     

燃气管网地震破坏快速评估方法研究

针对燃气管网基础资料难以获取的实际情况,利用有限数据开展燃气管网地震破坏的快速评估方法研究。基于历史震害统计分析结果,修订了燃气管网地震破坏等级划分方法;当燃气管网震害率模型不完备时,提出了类比供水管网震害率模型获得燃气管网震害率模型的方法。以东部发达城市上海市和西部石油城市新疆克拉玛依市为列,评估了2个城市在不同地震影响烈度下燃气管网的地震破坏情况,评估结果完全符合地震现场调查结论。     

Seismic loss estimation of non‐ductile reinforced concrete buildings

Non‐ductile reinforced concrete buildings represent a prevalent construction type found in many parts of the world. Due to the seismic vulnerability of such buildings, in areas of high seismic activity non‐ductile reinforced concrete buildings pose a significant threat to the safety of the occupants and damage to such structures can result in large financial losses. This paper introduces advanced analytical models that can be used to simulate the nonlinear dynamic response of these structural systems, including collapse. The state‐of‐the‐art loss simulation procedure developed for new buildings is extended to estimate the expected losses of existing non‐ductile concrete buildings considering their vulnerability to collapse. Three criteria for collapse, namely first component failure, side‐sway collapse, and gravity‐load collapse, are considered in determining the probability of collapse and the assessment of financial losses. A detailed example is presented using a seven‐story non‐ductile reinforced concrete frame building located in the Los Angeles, California. Copyright © 2012 John Wiley & Sons, Ltd.     

Seismic reliability assessment of urban water networks

We present a framework for the seismic risk assessment of water supply networks, operating in either normal or abnormal conditions. We propose a methodology for assessing the reliability of water pipe networks combining data of past non‐seismic damage and the vulnerability of the network components against seismic loading. Historical data are obtained using records of damages that occur on a daily basis throughout the network and are processed to produce‘survival curves’, depicting their estimated survival rate over time. The fragility of the network components is assessed using the approach suggested in the American Lifelines Alliance guidelines. The network reliability is assessed using graph theory, whereas the system network reliability is calculated using Monte Carlo simulation. The methodology proposed is demonstrated both on a simple, small‐scale, network and also on a real‐scale district metered area from the water network of the city of Limassol, Cyprus. The proposed approach allows the estimation of the probability that the network fails to provide the desired level of service and allows the prioritization of retrofit interventions and of capacity‐upgrade actions pertaining to existing water pipe networks. Copyright © 2013 John Wiley & Sons, Ltd.     

On the treatment of uncertainty in seismic vulnerability and portfolio risk assessment

In a related study developed by the authors, building fragility is represented by intensity‐specific distributions of damage exceedance probability of various damage states. The contribution of the latter has been demonstrated in the context of loss estimation of building portfolios, where it is shown that the proposed concept of conditional fragility functions provides the link between seismic intensity and the uncertainty in damage exceedance probabilities. In the present study, this methodology is extended to the definition of building vulnerability, whereby vulnerability functions are characterized by hazard‐consistent distributions of damage ratio per level of primary seismic intensity parameter—Sa(T₁). The latter is further included in a loss assessment framework, in which the impact of variability and spatial correlation of damage ratio in the probabilistic evaluation of seismic loss is accounted for, using test‐bed portfolios of 2, 5, and 8‐story precode reinforced concrete buildings located in the district of Lisbon, Portugal. This methodology is evaluated in comparison with current state‐of‐the‐art methods of vulnerability and loss calculation, highlighting the discrepancies that can arise in loss estimates when the variability and spatial distributions of damage ratio, influenced by ground motion properties other than the considered primary intensity measure, are not taken into account.     

Seismic vulnerability of bridges in transport networks subjected to environmental deterioration

This paper investigates the problem of management, maintenance and planning of interventions in transport networks located in seismic zones, in relation to the actual state of degradation of their most vulnerable elements, as bridges. The study consists in two phases: the first phase is concerned with definition of the seismic vulnerability of a typical bridge in the network, through the construction of fragility curves calculated taking into account the corrosion of the reinforcing steel as the main cause of environmental deterioration. Once the fragility curves of the deteriorated bridges are computed, the second phase consists in the analysis of the vulnerability of the transport network in which the bridges are included taking into account the modification of the traffic flows when bridge infrastructures are damaged. The results of this pilot study can be used as a first step for a proper allocation of economic resources in the planning of seismic retrofit interventions to minimize the overall risk and manage the immediate post-earthquake emergency phase and guide rescuers in reaching the affected and critical areas.     

基于震害资料的四川省藏式房屋地震易损性研究

搜集自开展地震灾害直接损失评估以来,四川境内破坏性地震震害资料,统计省内藏式房屋在不同烈度不同破坏等级下的破坏比,给出易损性矩阵;采用房屋结构整体易损性分析方法,依据藏式房屋易损性矩阵,通过烈度与地震动参数的对应关系,以对数正态分布函数为模型,对藏式房屋在不同地震动参数(峰值速度)下超越毁坏、破坏、基本完好的概率曲线进行拟合,给出易损性曲线,为其他结构类型房屋的易损性研究、灾害损失评估工作及震害预测提供参考。     

测震台站智能隔离防雷系统的设计与实现

介绍一种测震台站智能隔离防雷系统的设计实现。其电源部分设计为步进电机控制双电瓶交换充电、放电,保证设备与交流市电完全隔离;信号传输部分设计为通过无线局域网(WLAN)将测震信号传输到网关,再通过有线网络进行数据传输。此设计的优点是使测震核心设备与市电和外线完全物理隔离以达到最好的防雷效果。同时制作先进的NEMS传感器用于检测空间电磁场的变化,根据相应算法判断当地是否发生雷电,在附近有雷电发生时可控制断开信号线、市电等达到保护相关仪器的目的。     

基于地震动参数的RC框架结构易损性分析

以某典型的12层钢筋混凝土框架结构作为研究对象,研究基于非线性动力时程分析和地震动参数的RC框架结构易损性分析方法。首先采用静力pushover分析判定结构薄弱层,并确定结构性能(capacity)参数;然后应用非线性动力时程分析估计结构地震反应,研究以峰值加速度和基本周期加速度反应谱作为地震动参数结构反应的不确定性,并进一步分析结构地震需求(demand)参数与地震动参数的关系;在此基础上,分别建立该结构基于峰值加速度和加速度反应谱的易损性曲线,通过考虑场地条件对地震动特性的影响,研究场地条件对结构易损性的影响,结果表明不同场地条件下的结构易损性曲线有一定差异。应用本文方法,根据新一代地震区划图或地震安全性评价确定的地震动参数,可以直接估计结构在未来地震中出现不同破坏的概率,这在结构的抗震性能评估和地震损失预测中有一定意义。     

Statistical determination of significant curved I-girder bridge seismic response parameters

Curved steel bridges are commonly used at interchanges in transportation networks and more of these structures continue to be designed and built in the United States. Though the use of these bridges continues to increase in locations that experience high seismicity, the effects of curvature and other parameters on their seismic behaviors have been neglected in current risk assessment tools. These tools can evaluate the seismic vulnerability of a transportation network using fragility curves. One critical component of fragility curve development for curved steel bridges is the completion of sensitivity analyses that help identify influential parameters related to their seismic response. In this study, an accessible inventory of existing curved steel girder bridges located primarily in the Mid-Atlantic United States (MAUS) was used to establish statistical characteristics used as inputs for a seismic sensitivity study. Critical seismic response quantities were captured using 3D nonlinear finite element models. Influential parameters from these quantities were identified using statistical tools that incorporate experimental Plackett-Burman Design (PBD), which included Pareto optimal plots and prediction profiler techniques. The findings revealed that the potential variation in the influential parameters included number of spans, radius of curvature, maximum span length, girder spacing, and cross-frame spacing. These parameters showed varying levels of influence on the critical bridge response.     

Rapid estimation of earthquake loss based on instrumental seismic intensity: design and realization

As a result of our ability to acquire large volumes of real-time earthquake observation data, coupled with increased computer performance, near real-time seismic instrument intensity can be obtained by using ground motion data observed by instruments and by using the appropriate spatial interpolation methods. By combining vulnerability study results from earthquake disaster research with earthquake disaster assessment models, we can estimate the losses caused by devastating earthquakes, in an attempt to provide more reliable information for earthquake emergency response and decision support. This paper analyzes the latest progress on the methods of rapid earthquake loss estimation at home and abroad. A new method involving seismic instrument intensity rapid reporting to estimate earthquake loss is proposed and the relevant software is developed. Finally, a case study using the M _L4.9 earthquake that occurred in Shun-chang county, Fujian Province on March 13, 2007 is given as an example of the proposed method.     

地震油气储层的小样本卷积神经网络学习与预测

地震储层预测是油气勘探的重要组成部分,但完成该项工作往往需要经历多个环节,而多工序或长周期的研究分析降低了勘探效率.基于油气藏分布规律及其在地震响应上所具有的特点,本文引入卷积神经网络深度学习方法,用于智能提取、分类并识别地震油气特征.卷积神经网络所具有的强适用性、强泛化能力,使之可以在小样本条件下,对未解释地震数据体进行全局优化提取特征并加以分类,即利用有限的已知含油气井段信息构建卷积核,以地震数据为驱动,借助卷积神经网络提取、识别蕴藏其中的地震油气特征.将本方案应用于模型数据及实际数据的验算,取得了预期效果.通过与实际钻井信息及基于多波地震数据机器学习所预测结果对比,本方案利用实际数据所演算结果与实际情况有较高的吻合度.表明本方案具有一定的可行性,为缩短相关环节的周期提供了一种新的途径.     

Evaluation of analytical methodologies used to derive vulnerability functions

The recognition of fragility and vulnerability functions as a fundamental tool in seismic risk assessment has led to the development of more and more complex and elaborate procedures for their computation. Although these functions have been traditionally produced using observed damage and loss data, more recent studies propose the employment of analytical methodologies as a way to overcome the frequent lack of post‐earthquake data. The variation of the structural modelling approach on the estimation of building capacity has been the target of many studies in the past; however, its influence on the resulting vulnerability model for classes of buildings, the impact in loss estimations or propagation of the uncertainty to the seismic risk calculations has so far been the object of limited scrutiny. In this paper, an extensive study of static and dynamic procedures for estimating the nonlinear response of buildings has been carried out to evaluate the impact of the chosen methodology on the resulting capacity, fragility, vulnerability and risk outputs. Moreover, the computational effort and numerical stability provided by each approach have been evaluated and conclusions drawn regarding the optimal balance between accuracy and complexity. Copyright © 2013 John Wiley & Sons, Ltd.